Typically when we spec out the right exhaust system for one of our project cars our only concerns are fitment quality and proper airflow for maximum horsepower and torque production. And don’t forget aggressive sound, ’cause we’re not the strong silent types.

2/18

This time around, however, we have an additional consideration with our GM Performance Parts LS3 E-Rod project known as the EcoNova: We got cats. As part of the smog legality that comes with proper installation of the E-Rod system, four new production catalytic converters (just like those on a fifth-gen Camaro) must be installed into the exhaust system to the factory manifolds. So rather than header clearance issues, we’ve got converter clearance issues to contend with. That’s a first for us.

It’s also a first for the aftermarket, since cat-back kits don’t exist for ’70s-era cars. Actually, kits for our later-generation X-body cars like our ’77 Nova don’t exist. Or do they? We’ve long insisted that ’75-79 Novas used the same unibody architecture as ’68-74 cars, just wrapped with different sheetmetal—and kits do exist for those. We could have just started from scratch with a stack of tubing and bends, but we had a point to prove, and we figured that we could help create a new part number for a company and throw some love to the underserved fourth-gen X-body crowd.

So, we called Flowmaster Mufflers in Santa Rosa, California, to get one of their header-back American Thunder kits for third-gen Novas. They thought we were a bit crazy and recommended we take the EcoNova over to Big John’s performance in Santa Clarita, California, for a little help from master fabricator Stephen Munson in case our bet didn’t pay off.